Alloy



Patented Jan. 2, 1940 UNITED STATES PATENT orrlcs ALLOY Stephen P. Hackley, Stratford, Coma, assignor to The Bridgeport Rolling Mills Company,- Brtidgeport, Com, a corporation of Connecticu No Drawing. Application February 17, 1939,

Serial No. 256,863

peated cold rolling to produce predetermined,

tempers without intermediate anneals. It is also an object to provide an alloy which will be relatively unaffected by prolonged heat at temperatures to which it may be subjected when in nor- The alloy according to the invention isflespedially applicable to the production of products demanding these characteristics, for in- 20 stance electrical switches, fuse clips, plug receptacles, and the like, springs, sash chain, bassase.

hardware, etc. Tinned alloys heretofore employed for the particular uses contemplated herein have been found to be subject to such varlailar uses which have been found to be tempera- 25' 2 tion and uncertainty when they are worked, that the products fabricated from such alloys cannot alw be depended upon to perform their intended functions. I

The alloy according to the invention consists 30 of a mixture of copper, zinc, tin, and a small quantity of manganese, added as a flux. In preparing the alloy the ingredients are mixed in about the following proportions: copper 8''! to percent; zinc 9 to 13 percent; tin 2 to 4 percent. 38 These ingredients are melted in a crucible and a small amount of manganese is added as a flux. The proper amount of manganese may be deter-' is suitable for any purp se where toughness is desired, and is especially desirable where spring qualities are demanded, or where the metal is subjected to deformation in use. It has been found to have much higher electrical conductivity than other tinned alloys usually recommended for similar purposes, and is therefore especially usefulin the manufacture of electrical .devices.

The alloy has ductility. In practice it has been found that at 5#'s hard-that is, when rolled l0 five Brown 8: Sharpe numbers successively, and without intermediate annealsthe alloy averages about 83,000 lbs. per square inch in tensile strength with an elongation of 9 percent in 2 inches, while at 1l#s hard, ithas an average 15 tensile strength of around 100,000 lbs. per square inch with an average elongation of 6.6 percent in 2 inches. These figures are from tests employing a stock of .066 rolled to the two tempers cited.

- The alloy is practically unaffected when subjected to prolonged heat, tests having indicated that after heating for hours at 250 C. it showed reater hardness under a Rockwell B scale test.

As compared to other alloys intended for simmental and undependable, the alloy according to the invention has been found to have absolute uniformity in all tempers and in its various applications, so that it can be relied upon to perform characteristically under all conditions.

-zinc in the amount of 9 to 12 percent, tin in the amount of 2 to 4 percent, and manganese added as a flux in an effective amount not in excess of 2 percent, and said alloy being substantially free 40 of other constituents.

- STEPHEN P. HACKLEY. 

